(Reuters) - Merck ( MRK ) has acquired Modifi Biosciences for as much as $1.3 billion, gaining access to its experimental cancer therapies, the privately held biotech firm said on Wednesday.

As part of the deal, the U.S. drugmaker paid $30 million upfront. Modifi is also eligible to receive potential milestone payments of up to $1.3 billion in exchange for a new class of therapies, KL-50 - being developed against difficult-to-treat brain tumors, including glioblastomas.

New Haven, Connecticut-based Modifi is a pre-clinical stage company, which develops cancer therapies that aim to selectively kill cancer cells by modifying cancer DNA.

Modifi has raised $10.7 million to date in seed funding and is backed by investors including American Cancer Society's investment arm, BrightEdge.

Merck ( MRK ) has been in pursuit of eligible candidates that could potentially make up for a loss of revenue from its aging blockbuster cancer immunotherapy, Keytruda, which is set to lose its patent protection by the end of the decade.

Last year, the company struck a $5.5 billion deal with Japan's Daiichi Sankyo to jointly develop three of its targeted cancer therapies, known as antibody drug conjugates, which work like "guided missiles" against tumor cells while sparing healthy ones.